The product design and engineering workstream is just one element of the overall development programme required to get both the right product and a safe product to market. Its success relies on multiple inputs and parallel activities including risk management, human factors, clinical planning and intellectual property.
We have developed a detailed medical device programme management process to map out all of the activities that you need to plan and budget for to be executed in conjunction with the core engineering work. Our programme management process provides you with upfront visibility with regards to the overall development scope, timelines and cost (including your activities) giving you robust planning information to commit to your project milestones with confidence.
Understanding all of the deliverables ensures all stakeholder expectations are aligned and maximises the chance of commercial success.
This roadmap is an example of what needs to be considered to get a medical device to market. Non medical products will have similar roadmaps with different activities for consideration.
A Proof-of-Principle prototype (POP rig, POP prototype) is a prototype that has been designed and built to test the validity of a particular design approach. Its primary purpose will be to understand and reduce technical risk and therefore to confirm, guide or reject the design approach being tested. It is an experimental test rig that proves that the technology / science works, and may look at only a part of the final design. It will not look like, or necessarily work like the final device/instrument. The results of testing will be fed back into the Design Process.
Examples of proof-of-principal prototypes are;
- A selection of components made to the same design but in different materials, with the aim of assessing the most appropriate material
- A mechanism made from machined or rapid prototyped components to simulate the mechanism function. This could be made at a different scale and from different materials to those envisaged for the final product
- A test piece with a series of different flow channels machined into it to assess fluid flow and bubble rejection
- An electronics circuit built to test the performance of a proposed design
- Software written for a microcontroller development board to demonstrate in principle the ability to control a device or run a particular algorithm
- Software written on one platform that may ultimately be intended to be built for another platform (e.g. an algorithm prototyped on a PC but intended for inclusion in the embedded firmware)
It can sometimes be appropriate to construct proof-of-principal prototypes from model-making materials including wood, plastic sheet, cardboard, lego, meccano etc.
- The term Electronic Breadboard refers to early electronics POP prototypes to allow assessment of design options and to progress the schematic & circuit layout of the device. A breadboard may be hand wired or soldered using veroboard or similar prototyping substrates or built on an off the shelf development printed circuit board, or occasionally (particularly for low noise or RF circuits) be built on a specially designed PCB. Some of the layout of breadboard designs may be carried over into subsequent design iterations, but this is not guaranteed. Breadboard circuits should be considered learning and/or investigation tools for a section of circuitry built in hardware as an alternative to, or a refinement of, results obtained from simulation tools like Spice or Matlab.
- The term Mechanical Breadboard refers to early mechanical POP prototypes to allow the assessment of design options using reconfigurable components within, for example, fluidic or optical mechanical development systems.
- Model - This term is used to describe a representation of something within the prototype phase of a project. There are many ways of generating a model and the detail of what is meant by the term will be clarified by associated wording.
- CAD model refers to a CAD layout or detailed CAD design which enables visualisation of a 3D representation of a component or assembly on the screen of a PC
- Block model refers to a physical block model made from modelling materials such as wood, foam block etc.
- SLA model refers to a rapid prototype physical representation that could be either a preliminary SLA or a perfect cosmetic model. The type and finish of SLA will be defined in the proposal
- The term Model can also apply to a mathematical model on a spreadsheet, a Matlab model, a spice model of an electronics component or circuit or a logic flow model
A proof-of-principle prototype or breadboard is explicitly not a design that is immediately ready for manufacture and is unlikely to comply with all aspects of the product requirement specification.
An alpha prototype is designed to demonstrate the functions of a product. It is expected to work ‘most of the time’ and will provide useful feedback into the Design Process through Design Review. It will not necessarily look like the final product.
An alpha prototype will;
- Be designed to be made by techniques suitable for the final design, but not necessarily actually made by such techniques
- Typically be made in low volume (1-10) using manufacturing techniques such as machining and 'rapid-prototyping'
- Be expected to work 'most of the time' but will not exhibit the reliability and robustness that would be expected in a final product.
- Provide basic design functionality - the various functions will work but will not be tested, validated or calibrated
- Require further design refinement before final manufacture can commence
- Not be as robust as a final product. For example, it is likely to be more vulnerable to being dropped, paint finishes will be less durable etc
Provided initial testing is favourable, many of the design aspects of an Alpha Prototype may be maintained in the Beta Prototype design.
- Software Alpha Release - An alpha software release is for internal use by the development team, including the client. Alpha software is generally not fully tested and therefore unlikely to be stable. It will demonstrate the key features of the software and be suitable for use by experienced individuals for conducting studies to gather data and also to test for initial customer feedback. New features can be added to alpha software.
A beta prototype is designed to further demonstrate the functions of a product. It should look like and work like the final product but will not be produced using the factory manufacturing process/techniques.
A beta prototype will;
- Be designed to be made by techniques representative of the final design. Depending on the volume of manufacture, these could include injection moulding, extrusion, casting, machining etc.
- Typically be made in low volumes using manufacturing techniques such as machining and 'rapid-prototyping'
- Be expected to work with less intervention and maintenance than an Alpha prototype
- Provide basic design functionality - the various functions will work but will not necessarily have been fully tested, validated or calibrated. In some cases the purpose of the Beta Prototype will be for verification and further development.
- Require further design refinement (possibly including input from user testing of this
- Beta Prototype) before final manufacture can commence
- Not be as robust as a final product. For example, it is likely to be more vulnerable to being dropped, paint finishes will be less durable etc.
- Be suitable for pre-compliance EMC and electrical safety testing, although the prototypes would not necessarily be expected to pass all applicable tests at this stage.
Provided testing is favourable, much of the design of a Beta Prototype is likely to be maintained in the production design.
- Software Beta Release - A beta software release is for internal use and with “trial” consumer sites under supervision. Beta software should be significantly more stable than alpha software and will have undergone at least basic testing. A beta version of the software demonstrates all of the key features and may also be suitable for use by experienced individuals for conducting studies. On conclusion of the beta release phase, there is usually a “Feature Freeze” and ideally no new features should be added to the software after this point, instead, bug fixing and testing become the priorities. Addition of new features after feature freeze should be done through change control and significant changes may require a further beta release and retesting of the software.
A pre-production prototype is a device or instrument made very close to the production intent. It will typically be generated with parts made off-tool and in accordance with the relevant production process for that part (for example moulding a cover using injection moulding tool and following the process defined by the manufacturer). A pre-production prototype may not necessarily be produced by the final manufacturer/integrator and will be made in lower volumes than required as a production output and on a trial basis.
The aims of a pre-production prototype are to confirm whether the production design meets the product requirements specification and that it can be produced repeatably by the manufacturer. The pre-production prototype should ideally be representative of the final production device in terms of device robustness. The design and/or manufacturing processes may be modified if problems are identified.
Software Pre-Production Release - The pre-production release of the software (also called a Release Candidate) will be complete in every respect. This version of the software will have been thoroughly tested and will implement the agreed specification. Final verification of the software must then be completed on the pre-production prototype to ensure that all functions operate as expected on the target pre-production hardware.
Addition of new features at this stage is likely to require a return to the beta release phase and may necessitate complete retesting (regression testing) of the software.
The pre-production prototype may be submitted to regulatory testing by the client provided the design will not change for final production.
EG Technology does not offer warranties of any kind on pre-production prototypes or any output of the design process.
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